Find a trapezoid's area instantly from two parallel sides and height
Formula
Area = ((a + b) / 2) × h
a and b are the two parallel sides (bases); h is the perpendicular height between them.
Required Measurements
Results
Step-by-step
Key Facts
A trapezoid area calculator saves you from doing the arithmetic by hand. Just enter the two parallel sides (bases) and the perpendicular height, and the tool applies the standard formula — Area = ((a + b) / 2) × h — in an instant. Get the area, midsegment length, and optional perimeter with a clear step-by-step breakdown, all in one free online calculator.
The area of a trapezoid equals the average of its two parallel sides multiplied by the perpendicular height: Area = ((a + b) / 2) × h. Here a and b are the lengths of the two parallel sides (bases) and h is the vertical distance between them.
The height (h) is the perpendicular distance between the two parallel sides — measured at a right angle. The slant sides (legs) are the non-parallel sides that connect the bases at an angle. The area formula uses the perpendicular height, not the leg length.
The midsegment (or median) connects the midpoints of the two non-parallel legs. Its length equals the average of the two bases: (a + b) / 2. This is also the factor you multiply by the height to get the area.
Yes — expand the optional section and enter the lengths of both legs (the non-parallel sides). The tool will then calculate the full perimeter as a + b + c + d, where c and d are the leg lengths.